netflix in MBR?!

I installed archlinux in place of my OEM XP and I got a message saying that my MBR contained some netflix software and that I should tell my software suppliers to stop using MBR for such purposes.

I suppose that I should not worry about it, but it is weird. Since I used fdisk to delete all partitions and to create new ones, was arch not supposed to just rewrite MBR? How do I take netflix out of my MBR? Or I should better let it there ...

Re: netflix in MBR?!

Not software engineers; pointy haired bosses.

But whether the Constitution really be one thing, or another, this much is certain - that it has either authorized such a government as we have had, or has been powerless to prevent it. In either case, it is unfit to exist.-Lysander Spooner

Re: netflix in MBR?!

Thank you for the link. (No windows here, no problem.)

Sorry I can't remember any further details. I believe that I got the message when I ran

grub-install --target=i386-pc --recheck /dev/sda

from here. This is a laptop which had the option to play DVD's without booting into its native XP. (I never used this opportunity.) There have been one or two hidden partitions, probably used to implement this function.

I only need to zero some bytes in MBR, I suppose. I have a backup MBR and I believe that I can restore it in case. This software can, in theory, run under linux and hack my system?

Re: netflix in MBR?!

As far as I know, grub's smart enough to work around the foreign data, so you should be okay just leaving it alone. But if you want to make sure, you could try using dd to zero-out the first 63 bytes of your hard drive. That might destroy the partition table in the process, so make sure you backup everything important on the disk beforehand.

EDIT: Nah, that data is benign. It's just removing it can cause problem with the Windows software that put it there, and that software could just as easily put it back again, breaking grub. It's not a security vulnerability.

Re: netflix in MBR?!

WorMzy wrote:

As far as I know, grub's smart enough to work around the foreign data, so you should be okay just leaving it alone. But if you want to make sure, you could try using dd to zero-out the first 63 bytes of your hard drive. That might destroy the partition table in the process, so make sure you backup everything important on the disk beforehand.

EDIT: Nah, that data is benign. It's just removing it can cause problem with the Windows software that put it there, and that software could just as easily put it back again, breaking grub. It's not a security vulnerability.

Yes, I also believe that grub-install is not stupid enough to make GRUB to run any code it finds in MBR at the time it is run. As I said, no windows here, so no problems.

Re: netflix in MBR?!

This is crazy. Does anyone have even the slightest idea of why a desktop application like Netflix would need to write to the MBR? I'm having trouble wrapping my head around it.

Part of their DRM? I don't know how the MBR is laid out, but there may be some extra bytes they can use.

As far as I understood it, they use the spare sectors after the MBR and before the first partition for their DRM BS. The MBR itself does probably not have any unused bytes, although that totally depends on the boot loader.

Nevertheless, desktop applications like netflix are not supposed to write to raw sectors, ignoring the filesystem. I find this highly questionable.

Re: netflix in MBR?!

reminds of when TrueCrypt 5.0 came out a few years ago. It was the first version with full-disk encryption and people who activated photoshop couldn't boot their system anymore. Turned out that photoshop writes stuff to the MBR as part of its copy protection and therefore broke the TrueCrypt bootloader...